1. Field of the Invention
The present invention relates to a method of sorting non-defective/defective semiconductor lasers and, more particularly, to a sorting method appropriately used for semiconductor lasers having a GaInAs active layer and emitting a light with a oscillating wavelength of about 0.98 .mu.m.
2. Related Background Art
A semiconductor laser having a GaInAs active layer and emitting a light with a oscillating wavelength of about 0.98 .mu.m is desired to be put to practical use as an exciting light source of an Er-doped optical fiber amplifier. For this purpose, defective devices must be appropriately removed. As a sorting method of removing defective semiconductor lasers, a so-called accelerated test is generally used. In this method, a current larger than that in actual use is supplied for a predetermined period of time to remove initial detects. To acknowledge the initial defects, for example, a method on the basis of a change in threshold current before and after the accelerated test is used (Japanese Patent Publication No. 1-52912).
In the semiconductor lasers having a GaInAs active layer, however, rapid degradation occurs from one point during energization so that the semiconductor lasers reach a destruction state, i.e., a so-called sudden death is observed even in devices determined to be non-defective by the conventional accelerated test. That is, although the devices seem to have the same characteristics as those of a normal sample without exhibiting an increase in driving current to that point, they are suddenly degraded. Because of the high probability of such a sudden death in use, the GaInAs semiconductor lasers have not been widely used yet.